The present invention pertains to a cutting bit body, as well as a cutting bit using such cutting bit body, and a method of making the cutting bit body. More specifically, the present invention pertains to a cutting bit body for a cutting bit used for mining (e.g., coal mining), drilling (e.g., roof drilling in coal mining operations) and construction (e.g., road planing) applications, and a method for making the same, wherein the entire cutting bit body is a powder metallurgical body or at least one component of the cutting bit body is a powder metallurgical component.
Heretofore, conventional cutting bits used for mining and construction applications have included an elongate steel cutting bit body. Such cutting bits have also included a hard insert affixed to the axial forward end of the cutting bit body. The cutting bit is retained (in a rotatable fashion or in a non-rotatable fashion) at its axial rearward end to a holder or block During operation such as, for example, in a road planning application, the holder or block carrying the cutting bit is driven toward to impinge the earth strata thereby breaking or disintegrating the earth strata. As can be appreciated, severe forces exerted on the cutting bits and especially the cutting bit bodies. It is thus important that the cutting bit body possess optimum properties suitable to withstand such a severe operating environment for an acceptable duration.
The typical cutting bit body used in a cutting bit for mining and construction applications has an elongate steel body that is made via either conventional forging techniques or conventional casting techniques. While conventional forging or casting techniques produce a satisfactory steel cutting bit body, there are certain drawbacks connected with such a conventional steel cutting bit body.
Some of these drawbacks pertain to the method of manufacturing the cutting bit body. In this regard, the conventional steel body typically requires machining in order to complete the manufacture of the steel body. As one example, machining is the typical process used to form the socket in the axial forward end of the cutting bit body. While machining produces a satisfactory socket, there exist certain limitations or restrictions on the ability to machine (at least without undue costs or even at any cost) a socket of a relatively complex geometry to accommodate a hard insert of a complex geometry. Thus, it can be appreciated that it would be desirable to provide a cutting bit body made by near net shape manufacturing, as well as a method making the same, that does not need or require any machining, or requires only a minimal amount of machining, to complete the manufacture of the cutting bit body.
The properties of the cutting bit body impact the ability of the cutting bit to adequately withstand the severe operating environments inherent with mining and construction applications. The microstructure, the composition and the design of the cutting bit body help define the properties of the cutting bit body.
In regard to the microstructure of the cutting bit body, although current cutting bit bodies exhibit acceptable microstructures, it would be beneficial to provide a cutting bit body, as well as a method for making the same, that provides a cutting bit body with an improved microstructure such as for example, the microstructure would be more isotropic. It would also be desirable to provide a cutting bit body, as well as a method for making the same, that provides for flexibility in selecting the microstructure of the cutting bit body. In this regard, the cutting bit body would have a microstructure with different microstructural regions wherein each such region would have different properties. Thus, it would be desirable to provide a cutting bit body, as well as a method for making the same, that exhibits an improved microstructure including a more isotropic microstructure, as well as a microstructure with more design flexibility.
In regard to the composition of the cutting bit body, although current cutting bit bodies exhibit acceptable compositions, it would be beneficial to provide a cutting bit body, as well as a method for making the same, that provides a cutting bit body with an improved composition. Exemplary compositions would be those that have heretofore not been feasible using conventional forging or casting techniques. Other exemplary compositions would be certain ceramics and cermets that have heretofore been unavailable for use as a cutting bit body.
In regard to the design of the cutting bit body, although current designs of cutting bit bodies are acceptable, there exist certain drawbacks. Conventional cutting bodies are of a monolithic one-piece construction. Such a construction for a cutting bit body results in inherent restrictions on the design flexibility of the cutting bit body. It can therefore be appreciated that it would be desirable to provide a cutting bit body for a cutting bit that provides for improved design flexibility without current inherent restrictions. For example, it would be beneficial to provide a cutting bit body that would comprise a plurality of components to thereby expand the potential designs for the steel body. These components would take on any one of many geometries to provide enhanced properties for the cutting bit using such cutting bit body.